An Efficient Implementation of the Generalized Energy-Based Fragmentation Approach for General Large Molecules

An efficient implementation of the generalized energy-based fragmentation (GEBF) approach (Li, W.; Li, S.; Jiang, Y. J Phys. Chem. A 2007, 111, 2193) for treating a wide range of large molecules is presented. In this implementation, the fragmentation process can be automatically done for a general molecule, with only some functional groups defined by users. A new and fast scheme is designed for the generation of various subsystems and the derivation of their coefficients. The newly implemented GEBF approach has been applied to several large molecules including proteins, nucleic acids, and supermolecules with fused aromatic rings. Test calculations within the Hartree−Fock (HF) and density functional theory (DFT) framework demonstrate that the GEBF approach can provide reasonably accurate ground-state energies and optimized structures, which are in good agreement with those from conventional HF or DFT calculations. The GEBF approach implemented in this work can now be employed by nonexpert users to compute energies, optimized structures, and some molecular properties at various ab initio levels for a broad range of large molecules on ordinary PC workstations.